Add 72/21 and 7/5, Solve 3 9/21 + 1 2/5 as a fraction

Add 72/21 and 7/5

1^st number: 3 9/21, 2^nd number: 1 2/5

72/21 + 7/5 is 169/35.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 5 is 105

Next, find the equivalent fraction of both fractional numbers with denominator 105
For the 1st fraction, since 21 × 5 = 105,
72/21 = 72 × 5/21 × 5 = 360/105
Likewise, for the 2nd fraction, since 5 × 21 = 105,
7/5 = 7 × 21/5 × 21 = 147/105
Add the two like fractions:
360/105 + 147/105 = 360 + 147/105 = 507/105
507/105 simplified gives 169/35
So, 72/21 + 7/5 = 169/35
In mixed form: 429/35

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